There was about 2-1/2 gas remain in my 2001 BMW 740i when I tried to fill up the tank. After putting about 1 gallon of gas into the tank, the nozzle constantly shut off and the gas continuously overflew from the gas filler after I took out the nozzle. The dealer first told me the fuel hoses blocked. The next day told me the canister malfunction caused the problem even without checking the filler hoses. Another dealer told me it has nothing to do with the canister, and if the canister had had problem, the dash board computer would have indicated it. What is your opinion?
Most of todays vehicles have an “anti roll-over check valve” built into their filler necks. Basically, it’s a simple plastic or cork ball in a cage that the fuel flows around on its way into the tank. By overfilling the tank, you can float the check-ball up into the closed position where they sometimes get jammed.
Try inserting a flexible rod or stiff tube down the filler neck and you usually can dislodge the stuck check-ball. For sure, it has NOTHING to do with the carbon canister, which only works when the gas tank is sealed tight. With the cap removed, the tank is vented out the filler neck when being filled…
Thanks! But I did not overfill it. There were only about 3-1/2 gallons in the tank while the car has a capacity of 18-20 gallons. I guess I have been ripped off. I was trying to fill up the gas tank before hit the road back to CA after 2 days biz show in Las Vegas. I had the car towed to the dealer and they checked and found it was fine to start the engine, no leak on the gas tank, and said the fuel hoses must be blocked. And I was told they would not check the fuel hoses until the next day. They called me the next days saying the canister had to be replaced and it had to be ordered and over nighted from CA. I asked whether they had already checked the hoses,the answer was they would not check it until when they replace the canister. I am not surprised as I am a female. I am wondering how I can prove the canister replacement is not necessary. I am trying to get the money back because not only I had to pay the illegitimate parts and labor, but also I had to stay in the hotel in las Vegas for 2 extra days and nights to wait for the parts to arrive.
An incompetent mechanic is incompetent whether the customer is male or female. You can call the BMW regional representative and complain. They have recourse to real, live, automotive engineers. On the legal note, small claims court will be the place to address that question.
It is difficult to tell from here so we will have to make several suggestions.
That check valve (there are a couple of different kinds) may be the problem.
Especially if you have been in the habit of topping off the tank when you fill it up the charcoal canister may be the problem. It will need to be replaced.
If there has been an accident or repairs in that area or even if not, there are several hoses involved and if one of them is damaged loose etc. that could be the problem.
I will agree that usually if the charcoal canister is bad you would bet a CEL, but not always.
Finally there is a chance that the pump you are using is extra sensitive. You might try a different fuel source.
In the end the only way is to start taking things apart and checking or replacing parts.
Now for the unasked question. Why the heck are you going to a dealer for this? Dealers are no better (or worse) than independent mechanics for almost anything you might need done on your car. They will almost always charge more per hour and often more for parts and supplies. They also tend to look at repairs a little different than the independent.
A dealer may well recommend work that strictly may not be needed, but could be connected to the problem or maybe replace a part when a little repair would fix it ALMOST as good a new.
There is no need to bring your car to the dealer for any service other than service that is going to be paid for by a recall or original warrantee. During the warranty period be sure to have all required (as listed in the owner's manual) maintenance done and to document all maintenance work.
I suggest that most people would be better off finding a good independent (Not working for a chain) mechanic.
Note: Never ever use a quick oil change place. They are fast cheap and very very bad.
Thanks a lot! I feel secure to have a dealer to diagnose it. it is said that BMW mechanics have to attend a 2-year school which is run by BMW, in other words, they know better about BMW than others. You are right, dealers usually charge more. I really appreciate your suggestions. By the way, what does CEL stands for?
what does CEL stands for?
Check Engine Light. 
OK. You had a BMW dealer’s mechanics “diagnose” it. So, what’s the problem? CEL = Check Engine Light.
The problem happened when I was leaving Las Vegas and going back to CA. I had the dealer fixed it by changing the canister. After I was told by another dealer and I myself checked the function of the canister, I became more and more suspicious of the need to replace it.
Perhaps, if you started over, and kept events, decisions, and results, in chronological order, I might be understanding you.
Yeah they were called “step-students”. Most were pretty good,had big dreams of making alot of money. But the dealer could hire anyone at any level of training they wanted. BMW required a certain number of Master Techs based on how many cars were being sold. BMW would not allow Techs that didnt have training in a paticular model work on that car. This policy started with the 7series after your car,I could work on your car without “model orientation” but not the new 7series. I thought this was just fine as all the new work was warranty,BMW had very good warranty times. Good training. Everyone liked working on your model,except the 750 (the V-12)
Around 1:40 pm on May 7, 2008, the temperature being about 80 degree F, I was trying to fill up the gas tank of my 2001 BMW 740i before I got on the road back to home in CA after attending 2 days? business show in Las Vegas. With about 2-1/2 gallons of gas remain in my car - the fuel gauge indicating and the dash board computer showing 47 miles of driving range, I was unable to fill up the gas tank after putting about 1 gallon into the tank. The gas nozzle constantly shut off while I was trying to fill up the gas tank. The gas continuously overflew from the tank filler after I took the nozzle out. I called AAA and had the car towed and arrived at the dealer around 3:30pm.
Right after we arrived, the dealer did a checkup and found it was fine to start the engine and the dash board was showing no fault code except the airbag alert light which has been on for about 2 years after I changed the battery, and the gas tank itself was found no leak either. The initial diagnosis was the filler hoses blockage. I was told they would not check the fuel filler hoses until the next day and would let me know what was wrong. The next day, the dealer called me and told me that the carbon canister needed to be replaced. In addition, there was no part in stock and it had to be ordered and over-nighted from California with the total parts and labor $830. I asked if they had already checked the fuel hoses and eliminated the possibility of hoses blockage. The answer was that they would not check the hoses until when they replaced the canister. I felt this answer was not logical because their mechanic was so confident of the hoses clogging the day before, while now without checking the fuel hoses, they had already come to a conclusion of canister malfunction. I then called the service manager at a southern California BMW dealer whom I have known for years. I was told by that manager that, first, the carbon canister had nothing to do with being unable to fill up gas; second, even if there had been anything wrong with the carbon canister, the dash board computer would have shown the fault. His opinion was also fuel hoses clogging. Right after I hung up the phone, I passed that manager?s opinion to the dealer and requested to check the fuel hoses before replacing the canister, thus, if it was hoses-clogging, there would be no need to change the canister. The service representative then became angry with me by saying if I wanted them to fix it, they would have the canister replaced, or I took the car back.
So I stayed in Vegas 2 extra days and nights waiting for the canister to come in. They finally charged me $765.25 with a full tank of gas.
I think 750 has V-8, while 760 V-12.
Beg to differ never,a 760 in 2001 740I was the V-8 in 2001. No 6cy in the 7 series since the 735 in the U.S. 745 turbo in Europe. But I will ask about a 760 for 2008
So, the conclusion to the story is that they changed the charcoal canister, and, now, the fuel tank fills? Or, is there something more?
Yes, that’s the end.
Google BMW 2001 750il its a V-12 Google 2008 BMW 760il its a V-12. The OP car is a 2001.
When re-fueling, the tank is vented out the filler neck, NOT the charcoal canister…The hoses that connect to the canister are WAY to small to provide venting during refueling…There is a vent line that terminates just below the nozzle restrictor plate, allowing vapor out the open fuel filler…if the anti-rollover check valve was not the problem, then cold gasoline going into a hot fuel tank can sometimes boil, creating more vapor than the system can handle. Waiting a few minutes usually solves this problem.
Had the canister been plugged and defective, the car would STILL refuel normally. Not only that, the red check engine light would have been on before refueling was even attempted.
Mechanics don’t make any money freeing up check valves with a flexible rod shoved down the filler neck. They make GOOD MONEY replacing carbon canisters…
I appreciate your response. You are right the dealer just want to make money from it. I am in southern CA, while the dealer in Las Vegas. It would be inconvenient for me to take it to the small claim court. Any other way I can disute it and get some money back?
Caddyman,
I agree with what you said but I have a question.
If the purge valve becomes clogged that would cause the canister to become saturated, yes or no?
One thing I don’t understand is there is NO mention of there being a lit CEL.
If the canister is saturated the CEL would be on. Correct?